Shut-down discharge apparatus

ABSTRACT

An exhaust valve for venting highly contaminated gas from an enclosure includes a pivotally mounted valve flap which opens inwardly toward the source of contaminated gas. The exhaust valve also includes a tubular member suitably shaped to pass through the valve seat; the tubular member being normally positioned at the discharge side of the valve. When the valve flap is opened the tubular member is inserted through the valve seat to define a chamber which receives the valve flap whereby the valve flap and the valve seat are protected from direct exposure to the contaminated gas.

United States Patent 9 [H1 3,907,261 Legille Sept. 23, 1975 SHUT-DOWN DISCHARGE APPARATUS [75] Inventor: Edouard Legille, Luxembourg, Pnmary Emmmer cerald Dost Luxemburg [73] Assignee: S.A. Des Anciens Etahlissements Paul Wurth, Luxembourg. [57] ABSTRACT L b uxem urg An exhaust valve for venting highly contaminated gas Fllfldi Jilly 1974 from an enclosure includes a pivotally mounted valve [2H APPL NO: 491 35] flap which opens inwardly toward the source of contaminated gas The exhaust valve also includes a tubular member suitably shaped to pass through the valve Foreign Application Data seat; the tubular member being normally positioned at July 30, 1973 Luxemburg 63125 the discharge side of the valve. When the valve flap is opened the tubular member is inserted through the [52] US. Cl 266/17; 266/31 val e seat to define a chamber which receives the [SI] C218 7/00 valve flap whereby the valve flap and the valve seat [58] Field of Search 432/72; are protected from direct exposure to the contami- 266/15-17, 31 nated gas.

[56] References Cited 10 Claims, 1 Drawing Figure UNITED STATES PATENTS 2,200.488 5/1940 Clemmitt et al 266/3l X US Patent Sept. 23,1975 3,907,261

SHUT-DOWN DISCHARGE APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to controlling the flow of highly contaminated gases and particularly to relieving buildups of heated dirt laden gas. More specifically, this invention is directed to discharge valves for use on the exhaust mains of crude gas generators and particularly to blow off devices for mounting on blast furnace downcomers. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art While not limited thereto in its utility, the present invention is particularly well suited for use in association with methods of and apparatus for the reduction of ore such as, for example, in the manufacture of pig iron. It is well known that industrial reducing processes yield a considerable quantity oferude or top gas which is released from the reducing furnace by means of exhaust gas mains. Considering a blast furnace for purposes of explanation, the crude or top gas is at a high temperature and pressure and is heavily laden with particulate matter. Top gas conveying devices for association with blast furnaces are thus, in addition to being subjected to severe thermal stresses, also exposed to corrosion and erosion by entrained coarse dust particles. Such gas conveying devices, therefor, are subjected to abnormally heavy wear and consequently require great maintenance efforts.

Continuing with a discussion of a blast furnace environment, during normal periods of operation the exhaust gas mains, known in the art as downcomers, convey the top gas to a cleaning and cooling installation which, because of the high content of combustible constituents in the top gas, in turn releases the gas to a central gas supply system. Should a temporary shut-down of a single reducing furnace be required for any reason, since a plurality of furnaces are typically associated with a single cleaning and cooling installation, contin ued delivery of the top gas from the disabled furnace toward the central gas supply system must be prevented because of the low discharge pressure of the furnace which has been shut-down and because the top gas composition is substantially changed from that which is discharged from the furnaces which remain operative.

Safety considerations require the discharge or relief of the gases produced in the inoperative furnace as a precondition to the performance of any maintenance work. In this regard it is to be noted that a total stoppage rarely occurs since complete shut-down is incompatible with the modus operandi of reducing furnaces. It is therefore customary, in the case of shut-down of a furnace; i.e., when the reducing process is practically stopped; to release the crude or top gases which are continued to be produced into the atmosphere via a shut-down exhaust device. Such devices, which are often known in the art as shut-down discharge hats", are valve devices mounted on the summit of the downcomers and unlocked to the open position only during furnace shut-down.

The previously known shut-down discharge devices have consisted of a sliding or swinging diaphragm device, operated by means of an associated drive, or have been characterized by a valve flap which may be opened either outwardly or inwardly. The swinging or sliding diaphragm devices. as well as the discharge devices employing inwardly opening valve flaps, generally include a hat-like chimney which discharges the fur nace gases vertically into the atmosphere. It is. moreover, known to utilize these chimneys as flaring devices in the interest of burning off combustibles in the top gases.

The prior art shut-down exhaust devices of the type which employ a sliding or swinging diaphragm are subject, when the furnace is operative, to severe thermal stresses. Such prior art shut-down discharge devices have, accordingly, had a tendency to undergo physical distortion after a period of time. Any such distortion or warpage renders the shut-down discharge device either impossible to open or precludes the requisite tight sealing when the device is again shut. Also, when the movable closure device is in the open position the dirty and often steam moistened crude gas from the furnace will cause a deposit of particulate matter on the sealing surfaces of the device thereby impairing its sealing effectiveness.

The prior art shut-down discharge devices characterized by an outward opening valve member have the substantial disadvantage that, when in the closed position, they must counteract the forces produced by high furnace discharge pressure. This disadvantage, of course, is not present in the case of shut-down discharge devices which employ an inwardly opening valve flap member since the gas pressure operates to urge the closed flap against its sealing area. However, previous shut-down discharge devices employing an in wardly opening valve member have the disadvantage that the valve flap, when in the open position, is exposed to the dirty and often wet gas emanating from the furnace. Thus, as discussed above in the case of the shut-down discharge devices employing sliding or swinging diaphragms, inwardly opening valve flap type shut-down discharge devices are subjected to the corroding and eroding action of the gases being controlled and their sealing efficiency is significantly impaired by deposits of particulate matter.

To briefly summarize the deficiencies of the prior art, all previously known shut-down discharge devices have been characterized by a rapid decline of effectiveness and the need for frequent repair. Since the shut-down discharge hats are located at rather inaccessible points repair work is difficult and time consuming.

SUMMARY OF THE INVENTION The present invention overcomes the above briefly discussed and other deficiencies and disadvantages of the prior art by providing a novel and improved discharge valve for the exhaust mains of crude gas generators which will give trouble-free operation over long periods of time.

The objects of the present invention are accomplished by an exhaust valve consisting of an inwardly opening valve member or flap which is retracted from the gas stream when in the open position. The present invention also includes vent pipe means which are axially movable with respect to the seat with which the valve flap cooperates. The vent pipe means or tubulure is, with the valve in the normally closed position, disposed outwardly from and above the valve flap. When the valve is energized to the open position the tubulure is simultaneously inserted into the exhaust valve housing, through the valve seat, and thus protects the valve seat and valve flap from the deleterious effects of the dirty gas being vented to the atmosphere.

In accordance with a preferred embodiment of the invention the vent pipe means or tubulure includes a fuel injector and igniter. The tubulure thus may function as a flaring device to burn off combustible material in the gas being vented.

Also in accordance with a preferred embodiment of the invention, the exhaust valve housing and the movable tubulure cooperate to define an annular chamber which accomodates the valve flap when the shut-down discharge device is in the open condition. Means may be provided to deliver a cooling medium under pressure to this annular chamber.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing which is a schematic, crosssectional side elevation view of a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to the drawing, an exhaust valve assembly or shut-down discharge hat is indicated generally at l. The assembly 1 includes a valve housing 2 which is connected, by means of a lower flange 3, to a pipe segment 4. The pipe segment 4 is, in turn, connected by means of a flange joint 5 to the exhaust main 6 ofa reducing furnace. For reasons which will become obvious from the discussion below, the valve housing 2 is of larger diameter than the pipe segment 4.

The exhaust valve assembly 1 further includes a valve member or flap, indicated generally at 7, which has been shown by solid lines in the open position and by broken lines in the closed position. When in the closed or seated position the valve flap 7 is urged against a replaceable valve seat defining member or sealing ring 8. Movement of the valve flap 7 is controlled by an actuator, not shown but typically comprising a hydraulic jack, coupled to axle l0; rotational movement of axle 10 being transmitted to the valve flap 7 via an actuator arm 9. The axle it] penetrates the wall of valve housing 2 and the arm 9 is positioned within the valve housing.

In the embodiment shown the valve flap 7 is provided with a sealing ring l3 having a seating surface 14 of frustoconical shape. The sealing ring 13, which may be comprised of a soft metal, is mounted on a suitable base.

The valve seat defining member 8 has a seating sur face 15 of frustoconical shape and is afflxed to an upper flange 12 of valve housing 2 by means ofa plurality of bolts I]. If deemed necessary or desirable the seating surface l5 of the valve seat defining member 8 and the seating surface 14 of the valve flap 7 may be provided with a resilient sealing ring of a heat proof soft material such as an O-ring.

The valve flap 7 is provided. on its external or lower side, with a lifting lug l6. Lifting lug 16 may be employed during the removal and installation of the valve flap 7; such operations on the valve flap being performed conjointly with installation and/or removal of the sealing ring 8.

The exhaust valve assembly 1 also comprises vent pipe means which includes a tubulure 17. The diameter of tubulure I7 is less than that ol valve seat opening defined by sealing ring 8; the diameter of tubulure 17 being approximately equal to that of pipe segment 4. The tubulure I7 is mounted on a supporting arm 18 which slides vertically, by means ofa roller mechanism 19, in a vertically extending frame 20. The frame 20 is. mounted from the exterior of valve housing 2 and extends upwardly from the lower flange 3.

The tubulure I7 is shown in solid lines in the position it assumes with the valve flap 7 in the open position. The control of the positioning of tubulure 17 is coupled to the movements of the valve flap such that, if the flap 7 is fully open, the tubulure is fully inserted in the valve housing 2. When in the inserted position shown the tubulure 17 isolates the valve flap 7 and the sealing ring 8 from direct impingement of the furnace gas being vented. Thus, in the position shown, the tubulure l7 cooperates with the valve housing 2 to define an annular chamber 2| which communicates with the furnace exhaust main 6 by a small slot 22 only. The valve flap 7 and the sealing ring 8 are accordingly substantially protected against erosion, corrosion and deposits of the particulate matter entrained in the exhaust gases being vented. In the disclosed embodiment the tubulure 17 is provided, on its external surface, with stop members 24 which contact the outwardly extending flanges by which the sealing ring 8 is mounted on upper flange 12; the stop members 24 thus limiting the downward motion of the tubulure 17.

Additional protection against wear and the formation of deposits on valve flap 7, as well as thermal protection which prevents distortion of the valve flap, is provided by delivering a gaseous coolant to the chamber 21 defined between the tubulure l7 and the valve housing 2. In accordance with a preferred embodiment an inert gas or cleaned and cooled top gas is supplied, via the connector 23 disposed on valve housing 2, to the interior of chamber 21. The coolant will be delivered to chamber 21 at a somewhat higher pressure than that of the crude gas being discharged from the furnace so as to create a slight positive pressure differential between chamber 21 and the furnace exhaust main 6.

If deemed necessary or desirable, the vent pipe assembly may include, and in part define, a flaring device as indicated generally at 25. The flaring device consists of an extension 26 of tubulure 17 which is coaxial with a jacket 28. The extension 26 of the tubulure defines, at its upper end, a combustion chamber 27. The jacket 28 is open at its lower end in order to permit the ingress of sufficient air to support combustion within the flaring device 25. An injection nozzle 29 is disposed in tubulure extension 26 and a liquid or gaseous fuel is delivered to nozzle 29 via conduit 30. An igniter 31 extends inwardly through the wall of jacket 28 immediately above the upper end of tubulure extension 26. The crude gas/fuel/air mixture will. accordingly, be ignited by device 31 and combustibles in the gas being exhausted from the furnace exhaust main 6 will be burned. The flaring device 25 will be mounted for movement with the tubulure 17 on the carrying frame 20.

If flaring of the exhaust gases is not desired, all or a portion of the device 25 may nevertheless be furnished as part of the discharge control device assembly and the injection nozzle 29 may be supplied with steam or a dragging gas.

Should any maintenance work be required on the dis charge device 1, a plate 33 may be inserted between the connection flanges 5. Thereafter, a man-hole 32, disposed in the wall of valve housing 2, will be opened thus affording accessibility to the valve flap 7 when the exhaust control valve is in the open position.

The shut-down discharge device of the present invention has the advantage that the flow control member comprises an inwardly opening valve flap which, in the closed position, is pressed against a cooperating valve seat by the pressure within the furnace exhaust main 6 thus insuring reliable sealing. When the valve is open the valve flap is completely retracted from the exhaust gas stream and protected against the deleterious effects of the exhaust gas entrained particulate matter as well as being protected from thermal stresses. Thus. the service life of the discharge control devices of the present invention is substantially increased when compared to the prior art. The possibility of cooling and purging by means of a cooling gas delivered to the chamber 2| permits the use of resilient sealing material on the valve member thereby further enhancing the sealing reliability of apparatus in accordance with the invention.

While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

l. Gaseous discharge control apparatus comprising:

valve housing means, said housing means having an axis and first and second open ends, a first of said housing means open ends being coupled to a pressurized source of gas;

means mounted within said housing means intermediate of said open ends for defining an apertured valve seat axially aligned with said housing means second end;

a valve member pivotally supported within said housing means for cooperation with said valve seat, said valve member opening towards said housing means first end whereby the pressure of the source gasassists in sealing the valve member to the seat to prevent discharge of the gas;

elongated vent pipe means, said vent pipe means having an external shape commensurate with the shape of said valve seat and having a smaller crosssectional area than said valve seat: and

means mounting said vent pipe means from said valve housing means for movement along said axis whereby a first end of said vent pipe means may be inserted through the valve seat when said valve member is in the open position to protect said valve seat and said valve member from direct impingement of the gas being discharged.

2. The apparatus of claim 1 wherein said vent pipe means and said valve housing cooperate to define a chamber which receives said valve member when said valve member is in the open position.

3. The apparatus of claim 2 further comprising:

means for delivering a cooling medium to said chamber.

4. The apparatus of claim 1 wherein said valve member comprises:

a sealing gasket mounted on said valve flap; and

actuating means for said valve flap. said actuating means extending outwardly through the wall of said valve housing means.

5. The apparatus of claim 3 wherein said valve member comprises:

a sealing gasket mounted on said valve flap; and

actuating means for said valve flap, said actuating means extending outwardly through the wall of said valve housing means.

6. The apparatus of claim I wherein said vent pipe means comprises:

a tubulure;

a jacket coaxial with said tubulure, said jacket surrounding a portion of said tubulure including the second end thereof, said jacket being open at both ends and being positioned outwardly from said valve housing means second end with said valve member in the open position and said tubulure first end inserted through the valve seat; and

means for promoting combustion of unburned material in the gas adjacent the second end of said tubu lure.

7. The apparatus of claim 2 wherein said vent pipe means comprises:

a tubulure;

a jacket coaxial with said tubulure, said jacket surrounding a portion of said tubulure including the second end thereof, said jacket being open at both ends and being positioned outwardly from said valve housing means second end with said valve member in the open position and said tubulure first end inserted through the valve seat; and

means for promoting combustion of unburned material in the gas adjacent the second end of said tubulure.

8. The apparatus of claim 7 wherein said valve member comprises:

a valve flap;

a sealing gasket mounted on said valve flap; and

actuating means for said valve flap, said actuating means extending outwardly through the wall of said valve housing means.

9. The apparatus of claim 8 further comprising:

means for delivering a cooling medium to said chamber.

10. The apparatus of claim 9 wherein said means for promoting combustion comprises:

means for injecting a combustible fuel into said tubulure at a point intermediate the ends of said jacket.

* I? l l 

1. Gaseous discharge control apparatus comprising: valve housing means, said housing means having an axis and first and second open ends, a first of said housing means open ends being coupled to a pressurized source of gas; means mounted within said housing means intermediate of said open ends for defining an apertured valve seat axially aligned with said housing means second end; a valve member pivotally supported within said housing means for cooperation with said valve seat, said valve member opening towards said housing means first end whereby the pressure of the source gas assists in sealing the valve member to the seat to prevent discharge of the gas; elongated vent pipe means, said vent pipe means having an external shape commensurate with the shape of said valve seat and having a smaller cross-sectional area than said valve seat; and means mounting said vent pipe means from said valve housing means for movement along said axis whereby a first end of said vent pipe means may be inserted through the valve seat when said valve member is in the open position to protect said valve seat and said valve member from direct impingement of the gas being discharged.
 2. The apparatus of claim 1 wherein said vent pipe means and said valve housing cooperate to define a chamber which receives said valve member when said valve member is in the open position.
 3. The apparatus of claim 2 further comprising: means for delivering a cooling medium to said chamber.
 4. The apparatus of claim 1 wherein said valve member comprises: a valve flap; a sealing gasket mounted on said valve flap; and actuating means for said valve flap, said actuating means extending outwardly through the wall of said valve housing means.
 5. The apparatus of claim 3 wherein said valve member comprises: a valve flap; a sealing gasket mounted on said valve flap; and actuating means for said valve flap, said actuating means extending outwardly through the wall of said valve housing means.
 6. The apparatus of claim 1 wherein said vent pipe means comprises: a tubulure; a jacket coaxial with said tubulure, said jacket surrounding a portion of said tubulure including the second end thereof, said jacket being open at both ends and being positioned outwardly from said valve housing means second end with said valve member in the open position and said tubulure first end inserted through the valve seat; and means for promoting combustion of unburned material in the gas adjacent the second end of said tubulure.
 7. The apparatus of claim 2 wherein said vent pipe means comprises: a tubulure; a jacket coaxial with said tubulure, said jacket surrounding a portion of said tubulure including the second end thereof, said jacket being open at both ends and being positioned outwardly from said valve housing means second end with said valve member in the open position and said tubulure first end inserted through the valve seat; and means for promoting combustion of unburned material in the gas adjacent the second end of said tubulure.
 8. The apparatus of claim 7 wherein said valve member comprises: a valve flap; a sealing gasket mounted on said valve flap; and actuating means for said valve flap, said actuating means extending outwardly through the wall of said valve housing means.
 9. The apparatus of claim 8 further comprising: means for delivering a cooling medium to said chamber.
 10. The apparatus of claim 9 wherein said means for promoting combustion comprises: means for injecting a combustible fuel into said tubulure at a point intermediate the ends of said jacket. 